The aim of the present study was to evaluate in 111 ejaculates from fertile men membrane integrity of spermatozoa before selection and sperm motility, and sperm concentration and chromatin integrity before and after selection of motile spermatozoa. Assay of sperm chromatin integrityA smear of semen was stained with a 1% acridine orange solution (Sigma Chemical Co.USA) in Sorensen phosphate for five minutes and the spermatozoa were observed under a fluorescent microscope (λ = 490 nm).The number of normal sperm with double stranded DNA (green fluorescence) or abnormal sperm with single stranded DNA (red fluorescence), was recorded (17).